Proposed is the development of an extremely compact ultrasound concentric sector biopsy imaging transducer and signal-processing subsystem having the capability of imaging the entire path of a biopsy needle in the plane of view, so as to visualize and biopsy a brain tumor through a single burr hole with the safeguards of image markers. This investigation focusses on the development of a compact probe providing high resolution sector image through a small (1.5cm) diameter acoustical window and a central needle access hole. Signal-processing electronics, drive control electronics, and marker electronics will be designed as a subsystem to optimize probe performance. Benefits that will be derived from this research include: 1. Simulataneous visualization and penetration of the anatomical region to be biopsied or aspirated with the needle trajectory always within the field of view. 2. Small contact area for visualization and biopsy for difficult applications (e.g. neurosurgery). 3. Improved safeguards and accuracy in biopsy procedures. 4. Reduction in medical liability invasive procedures.